Accumulator structure



Dec. 21, 1954 E. J. svENsoN 2,697,449

ACCUMULATOR STRUCTURE Filed Dec. 14, 1948 INVEN TOR.

United States P 2,697,449 ACCUMULATOR STRUCTURE Ernest J. Svenson, Rockford, Ill.

Application December 14, 1948, Serial No. 65,197

3 Claims. (Cl. 138-30) This invention relates to a new and improvedaccumulator structure and more specifically it relates to a particular ai'rangement of an accumulator diaphragm structure.

- Accumulators, as is well known, are frequently used to smooth the flow of a liquid from a reciprocating pump, or to store up a quantity of liquid'being pumped in a hydraulic system so that a pump may be used which is of a smaller capacity than the maximum demand upon the system. It would, of course, be possible to use a pump equal in capacity to the maximum demand on the system, but this is not desirable when the demand is intermittent as it so frequently is in hydraulic systems, because, as is well known, it is uneconomical to operate a large pump at or near its full capacity only a small fraction of the time. In'thein'tere's'ts of ease and economy of installation and in economy'of operationpit is desirable that a pump should" be used which is operating at or near its peak capacity as muchof the time as possible. v Accordingly accumulators are used, t i

Generally accumulators have fallen into one of two classifications. In the first of these, nothing separates the liquid from the gas in the accumulator. This leads to several difliculties, among them that the gas in large or small amounts dissolves in the liquid and is carried off by it thus adulterating the liquid and making it imperativethat gas be added at frequent intervals. Furthermore, it is necessary in this type of accumulator that the gas should at all times be above the liquid. If the structure is tilted to any great degree, or if the liquid is exhausted from the accumulator, the gas will be exposed directly to the liquid outlet and will blow out. To overcome this difliculty, it has been suggested that a flexible diaphragm should be interposed between the gas and the liquid. A simple, flat diaphragm of rubber or other flexible material serves to separate flre two media, but as it must be stretched in addition to being constantly flexed, its life is very short. Other accumulators have been built using a diaphragm in the form of an inner tube such as is used in a common automobile tire, and in a variety of kindred shapes in which the tubing proper forms an enclosure for the gas. paratively difiicult and expensive to make and installation is often diflicult. Furthermore, such diaphragm structures are short lived.

Accordingly, it is an object of this invention to provide an accumulator having a diaphragm so that the gas will not blow out if the structure is tilted or exhausted of liquid.

It is further an object of this invention to provide such an accumulator having a diaphragm which is not stretched and has a long life and which is simple and easy to manufacture.

A still further object of the invention is to provide an improved mounting and securing means for the flexible diaphragm of an accumulator, wherein the mounting and securing means permits free diaphragm flexibility while at the same time protecting the diaphragm and promoting the durability and long life thereof in service.

Other and further objects and advantages of the present invention will be apparent from a perusal of the following specification with reference to the accompanying drawings in which:

Figure l is a cross-sectional view of the accumulator structure taken on the line 1--1 of Figure 2;

Figure 2 is a bottom view of the accumulator structure taken along the line 22 in Figure 1 showing most These are com-' 65 mistermed synthetic rubbers.

2,697,449 Dec. 21, 954

l Patented Figure 3 is an enlarged fragmentary sectional view of e uncture 'hetweenth'e diaphragm and the two partsof the housing; and.

igu're 4 11s a diagrammatic v 'ew of a hydraulic circuit show ng the accumulator m use. j

The accumulatorstructure may be mounted in a'circularhole 1 in a frameor other support 3. The cup shaped upper portiony5 of the accumulator housingis fastened totheframe 3by a pluralityjof screws 6 fitted through screw holes inflange 7 which constitutes an -1ntegral part pf the upperi part 5 of, the housing. The

screws 6 a'rethreadedinto holes9 in the frame 3." An

inletpipe 11 isthreaded into the top of the upper cup shaped portion 5of the housirig'and provides for ingress and egress of ,the liquid. A lo wer flat member 13 completes thefaccu'mulator hou'sfing'and'isiheld to the upper part Sgby screws 15 which threadingly'engage the upper portion" of .the housing-in screw, holes 16. Extended .p ort ions 17.1 are, provided onthe's'ide s of the upper cup "shaped p0rt1o'nf5 of, the housing to accommodate the "screwsl5."' 1 f A rubber diaphragm 19'of unique construction is held between the two portions of the accumulator housing dividing the interior of said housing into two' chambers. This'draphragm has a thickened central section 20 and 1 s he1d'by pressureon. a rubber flange21 formed integralwit htheremainder o'f'the diaphragm at 'the' pe- "riphery, thereof. ,A.shoulder.,23 onthelowermember 13 o f the accumulator housing laterally confines the flange "21 and prevents theflange from being forced outwardly with respect to..the'housing. A small space 25 is left between the shoulder 23'and,the flange 7 of the upper portion of thehousing. This space is on the order of a 40 upon to. control the clamping. pressure, it is obvious that screws to a known tension while maintaining the aforementioned clearance, a predetermined pressure may at all times be applied to the flange 21 and complete flexibility is thus present at the corner 27 between the flange 21 and the main body portion of the diaphragm The mounting for the flange 21, as described, thus serves the dual purpose of preventing lateral spread of the flange while also permitting the clamping pressure upon the flange to be accurately gauged by the bolt tension to the requirements of any particular installation.

in this manner a tight clamping pressure may be used, 1f desired, without danger of distorting the flange, and without premature deterioration thereof, while at the same time permitting a completely free flexing of the diaphragm adjacent the secured flange which further promotes the life of the structure.

The diaphragm 19 which has been spoken of as being composed of rubber could, of course, be constructed of any one of a number of the synthetic elastomers generally Some of these materials are better adapted than rubber to continued flexing and are less subject to deterioration by the media contained in the accumulator.

The upper chamber 29 demarcated in the accumulator housing by the diaphragm 19 is filled with the liquid being pumped and as was before mentioned is connected to the liquid by inlet pipe 11. The lower chamber 31 formed in the housing by the diaphragm 19 is filled with gas. Whereas it is possible to fill this chamber with air,

it is preferred that some inert gas such as nitrogen should be used. Nitrogen is inexpensive and does not have the deleterious effects on rubber that air has. The gas is admitted to the lower chamber 31 through a passageway 33 and a valve 35 such as is commonly used in automobile tires. I

Whenever the pressure on the liquid in the chamber 29 becomes less than that of the gas confined in chamber 31, the gas expands forcing the diaphragm .19 upwards, thus expelling the liquid through the pipe 11. As the pressure on the liquid is increased by a pump or the like, some of the liquid re-enters the chamber 29 vvia the pipe 11 and the diaphragm 19 is again forced down compressing the gas 31.

In Figure 4 an operating hydraulic circuit is diagrammatically illustrated, showing the accumulator in use.

A pump 41 draws liquid such as oil from a reservoir 43 by means of a pipe or conduit 45, the oil being propelled through a check valve 47 and line 11 to the accumulator structure. A by-pass line 49 returns to the reservoir through an adjustable relief valve 51 by which the maximum delivery pressure of the pump and the maximum accumulator pressure may be controlled. A -line' 53 leads to the operated device, as shown. When the volumetric delivery of the pump exceeds the requirements of the line 53, the accumulator is charged with liquid, compressing the gas therein, as previously described. At such times when the requirements of the pipe line 53 exceed the volumetric delivery of the pump, the liquid stored within the accumulator under pressure becomes available to augment the pump delivery and supply the operating requirements of the operated device.

It is apparent that variations from the foregoing specification may be made without departing from the spirit of the invention. The invention is accordingly to be limited only as indicated by the following claims.

I claim:

1. A fluid pressure accumulator of the flexible diaphragm type and comprising a pair of casing members, one of said casing members being recessed to define with the other casing member, a chamber therebetween of predetermined size and shape, said casing members having complementary flange portions secured together, and a flexible diaphragm made in the shape of a flanged cup disposed within said chamber and dimensioned relative to said chamber to substantially prevent stretching of the diaphragm during its movements between the limits of travel defined by said casing members, said cup having the side wall thereof provided at its inner end with a gradual reversely curved portion locating the cup bottom intermediate the ends of the side wall and having the cup flange clamped between the flange portions of said casing members, the side wall of the cup projecting in one predetermined direction along and juxtaposed to the wall of said recessed casing member, the other casing member preventing movement of the bottom of the cup away from said recessed casing member beyond a predetermined position such as to maintain the side wall of the cup projecting into said recessed casing member in the same said one predetermined direction and in juxtaposition with respect to the wall thereof adjacent the cup flange and having a surface portion inwardly of the cup side wall substantially fiat and coplanar with its flange portion for preventing any movement of the side wall of the cup adjacent its juncture with the cup flange in a direction opposite to said predetermined direction whereby to prevent working of the cup wall at the flange juncture and effect bending of the diaphragm along the curved portion between the bottom and side wall of the cup during its movement within the limits of travel defined by said casing members.

2. A fluid pressure accumulator as defined in claim 1, wherein the diaphragm cup side wall portion and the diaphragm flange portion are substantially perpendicularly disposed relative to each other, defining a substantially right angular line of juncture therebetween.

3. A fluid pressure accumulator as defined in claim 1, wherein the reversely curved portion is extended toward the said other casing member when the diaphragm is in normal position, providing a cup within a cup, in the cup portion of the diaphragm.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 381,731 Walker Apr. 24, 1888 2,241,056 Chilton May 6, 1941 2,300,722 Adams et al. Nov. 3, 1942 2,324,701 Herman July 20, 1943 2,345,475 Herman et al Mar. 28, 1944 2,401,791 Overbeke July 11, 1946 2,489,491 Johnson Nov. 29, 1949 2,563,257 Loukonen Aug. 7, 1951 2,642,090 Barr June 16, 1953 FOREIGN PATENTS Number Country Date 841,468 France May 22, 1939 

